I'm 52 with one very bad knee caused by a serious accident 20 years ago. It's a bummer.


I can't use a bike at all, stationary or not. What I can do is a rowing machine, or a ski machine (cross trainer??). No trouble at all.
Also I came across a machine in a gym which was like a bike for arms. You sit and turn the handles. It's exhausting and effective.

All I need now is the motivation!